The prior art includes a wide variety of interfaces for supplying gases to a patient. These interfaces are frequently used for delivering a stream of gases to a person being treated for a sleep disorder, or for delivery of supplementary gases to a user who is breathing unaided, but who requires these supplementary gases. These users typically wear the interface in a hospital Intensive Care Unit (ICU), other hospital wards or a home sleeping environment. Comfort even under conditions of patient movement is a major consideration.
The following are examples of interface types known in the prior art.
The prior art includes a nasal cannula interface. A typical nasal cannula interface includes a plenum portion and entry tubing or a manifold section (symmetric or single sided) that rests against the upper lip of the user in use, and a pair of open-ended prongs, which protrude from the entry tubing and extend into the nostrils of the user in use to supply the patient with gases. Generally, but not always, these prongs are sized and shaped so that they do not seal against the nostrils of a patient. Nasal cannulae are used because these are advantageous in certain situations. For example, in circumstances where a patient is breathing normally, but requires supplementary gases such as supplementary oxygen. The existing market for nasal cannula is well serviced by devices suitable for delivery of gases in the 0 to 5 liters per minute range. These devices are typically supported by a double entry lumen of small diameter (2-3 mm range) that supplies both sides of the nasal cannula and provides even or equal airflow to each nasal prong. These devices work well for the delivery of dry gas flows of between 0 to 5 liters per minute, when the patient is self-breathing, and it is not necessary for the cannula prongs to seal against the nares of a user. A user will entrain the supplementary gases provided from the cannula along with atmospheric air as they inhale normally.
An example of a nasal cannula interface that seals against the nostrils is the Nasal-Aire interface made by Innomed, where gases are provided to the interface and the prongs by conduits or hoses that extend from the users nose across their cheeks, over their cars and around the back of their head.
WO 2008/060295 describes a non-sealing cannula that includes nasal prongs. There are many configurations described. The nasal prongs are adapted to deliver air to a patient's nasal passage and the different embodiments of prongs described include various external features, and may include passages that pass through the wall of the prongs to allow sensors or similar to measure the properties of gases in the prongs.
The prior art also includes several other types of interface, which are included here for general context, but which are not directly relevant. These are outlined briefly below.
A nasal mask, which includes a perimeter seal that seals across, down each cheek alongside the nose and along the surface of the upper lip. The entire enclosed space is pressurised and the recipient may inhale the pressurised gas from the enclosed space. An example is the Flexifit 405 nasal mask sold by Fisher & Paykel Healthcare.
A full face mask, which includes a perimeter seal that extends across the bridge of the nose downward along each cheek beside the nose to the jaw and along the jaw below the lower lip. The perimeter thereby encloses both the nose and mouth. The entire space within the mask frame is pressurised. The recipient may breathe the pressurised gas from the space through either the nose or mouth. An example is the Flexifit 431 interface sold by Fisher & Paykel Healthcare.
An oral interface including an oral appliance that fits within the user's mouth. An example is the Fisher & Paykel Healthcare Oracle interface.
Nasal pillows, which are intended to seal around the perimeter of a user's wires in use, and deliver a stream of pressurised gases to the nasal cavity of a user. A number of different types of nasal pillow are described and shown in WO 2008/014543.
In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art.
It is an object of the present invention to provide a nasal interface which goes some way to overcoming the disadvantages of the prior art or which will at least provide the industry and public with a useful alternative.